By Kelli Whitlock Burton
Demonstrating that vitamins, but not cocoa, can be beneficial is the exact opposite of what researchers expected. Even so, the results offer an interesting new direction for future studies, lead researcher Dr. Laura D. Baker, professor of gerontology and geriatric medicine at Wake Forest School of Medicine in Winston-Salem, North Carolina, told Medscape Medical News.
"This study made us take note of a potential pathway for cognitive protection," Baker said. "Without this study, we would never have looked into that avenue."
The full results have been published online in Alzheimer's and Dementia.
The COSMOS-Mind study is a substudy of a larger trial called COSMOS. It investigated the effects of cocoa extract and a standard multivitamin-mineral (MVM) supplement on cardiovascular and cancer outcomes in more than 21,000 older participants.
In COSMOS-Mind, researchers tested whether daily intake of cocoa extract versus a placebo and of a multivitamin-mineral versus a placebo improved cognition in older adults.
More than 2,200 participants aged 65 and over enrolled and were followed for 3 years. They completed telephone tests at baseline and annually to assess memory and other cognitive abilities.
The results showed that cocoa extract had no effect on overall cognition compared to the placebo. However, daily use of multivitamins did show significant benefits on overall cognition compared to the placebo.
The beneficial effect was more pronounced in participants with a history of cardiovascular disease.
The researchers found similar protective effects for memory and executive function.
Baker suggested that a possible explanation for the positive effects of multivitamins could be the increase in essential micronutrients and minerals they provide.
"With nutrient-deficient diets, plus a high prevalence of cardiovascular disease, diabetes, and other medical comorbidities that we know affect the bioavailability of these nutrients, we may be dealing with older adults who are below the optimum level in terms of their essential micronutrients and minerals."
"Even suboptimal levels of essential micronutrients and minerals can have significant consequences for brain health."
More research is needed
Despite the intriguing results, more work is needed before the findings can influence nutritional guidance, according to Dr. Maria C. Carrillo, chief scientist at the Alzheimer's Association.
"While the Alzheimer's Association is encouraged by these results, we are not prepared to recommend the widespread use of a multivitamin supplement to reduce the risk of cognitive decline in older adults," Carrillo said in a statement.
"For now, and until more data is available, people should talk to their healthcare providers about the benefits and risks of all dietary supplements, including multivitamins," she added.
Baker agreed, noting that the study was not designed to measure multivitamin use as a primary outcome. Furthermore, nearly 90% of the participants were non-Hispanic white, which is not representative of the general population demographics.
The researchers are now designing another, larger trial that will include a more diverse group of participants. Its specific goal will be to learn more about how and why multivitamins appear to offer a protective effect on cognition, Baker noted.
The study was funded by the National Institute on Aging of the National Institutes of Health. Baker and Carrillo do not report any relevant financial relationships.
Alzheimer's Disease. Published online September 14, 2022. Full text